JP2007311084A - Electrolyte, member for battery, electrode, and all-solid secondary battery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve ion conductivity of an electrode and a solid electrolyte layer which are constituent components of an all-solid secondary battery and improve battery characteristics of the all-solid secondary battery. <P>SOLUTION: This is an electrolyte which is composed of in substance only a lithium ion conductive solid substance, and the film thickness is 500 μm or less. The electrolyte is formed by a blast method or an aerosol deposition method. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a solid electrolyte, a battery member, and an all-solid secondary battery. More specifically, the electrode layer or the electrolyte layer does not contain a binder material or the like, and is a solid electrolyte substantially made only of an electrode material or a lithium ion conductive solid material, a battery member, an electrode, and a lithium ion secondary battery using the same. The present invention relates to an all solid state secondary battery such as a secondary battery.

In recent years, the demand for secondary batteries such as high-performance lithium batteries used in personal digital assistants, portable electronic devices, small household power storage devices, motorcycles powered by motors, electric vehicles, hybrid electric vehicles, etc. has increased. Yes.
As the applications used expand, further improvements in safety and performance of secondary batteries are required.
In order to ensure the safety of the lithium battery, it is effective to use an inorganic solid electrolyte instead of the organic solvent electrolyte.

Inorganic solid electrolytes are nonflammable in nature and are safer materials than commonly used organic solvent electrolytes. Therefore, development of an all-solid lithium battery with high safety using the electrolyte is desired.
In an all-solid lithium battery, conventionally, a binder is used to form a molded body of a solid electrolyte layer such as a sheet or a thin film. However, when a binder is mixed in the electrolyte layer, there is a problem that the ion conduction path is cut and the ionic conductivity of the solid electrolyte layer is lowered.

Therefore, although an electrolyte layer made of only a solid electrolyte has been studied, it is difficult to form a single layer thin film made of only a solid electrolyte.
Moreover, since Li ion conductivity in the electrolyte when the battery is configured depends on the thickness of the electrolyte layer, it is desired to reduce the thickness of the solid electrolyte layer.

In order to solve such a problem, Patent Document 1 discloses a method of manufacturing an electrode for a chemical battery by a cold spray method in which active material particles are sprayed and adhered to a current collector together with an air current. However, in this method, since it is necessary to use an air flow in which a gas heated to 300 to 500 ° C. is made a supersonic flow, there is a problem that usable active material particles are limited to silicon or the like. Moreover, since a high-temperature and ultra-high-speed air flow is required, a precise device is required.
JP-A-2005-310502

  The present invention has been made in view of the above-described problems, and improves ion conductivity of electrodes and solid electrolyte layers that are constituent members of all-solid secondary batteries, and improves battery characteristics of all-solid secondary batteries. Objective.

According to the present invention, the following electrolyte, battery member, electrode, and all-solid secondary battery are provided.
1. An electrolyte consisting essentially of a lithium ion conductive solid material and having a film thickness of 500 μm or less.
2. 1. An electrolyte formed by a blast method or an aerosol deposition method.
3. A battery member having a current collector and one or two electrolytes in at least a part of the current collector.
4). An electrode having a current collector and an electrode material layer formed on at least a part of the current collector by a blast method or an aerosol deposition method.
5). An all-solid secondary battery comprising at least one of the electrolyte according to any one of 1 to 4 above, a battery member, and an electrode.
6). 6. The all-solid-state secondary battery according to 5, wherein the electrolyte comprises lithium sulfide and diphosphorus pentasulfide and / or simple phosphorus and simple sulfur.

  According to the present invention, the ionic conductivity of the electrode of the all solid state secondary battery or the solid electrolyte layer can be improved. By using this electrode or electrolyte, the battery characteristics of the all-solid-state secondary battery can be improved.

A. Electrolyte The electrolyte of the present invention consists essentially of a lithium ion conductive solid material and has a film thickness of 500 μm or less.
“Electrolyte consisting essentially of a lithium ion conductive solid substance” means that the electrolyte does not contain a so-called “tethering” component such as a binder (binder) like the conventional electrolyte layer, and the electrolyte is lithium ion conductive. It means that it consists only of solid substances.
Thus, ion conductivity can be improved by forming electrolyte.

  In the present invention, the thickness of the electrolyte is 500 μm or less. When it is thicker than 500 μm, the mobility of Li ions in the electrolyte is not sufficient, which is not preferable. Preferably, the thickness of the electrolyte is 0.01 to 500 μm, more preferably 0.1 to 10 μm.

  In the electrolyte, in order to improve the ionic conductivity, it is important that the solid electrolyte particles are in close contact with each other, have many junctions and surfaces between the particles, and ensure more ion conduction paths. For this reason, the smaller the space generated in the gaps between the solid electrolyte particles (the ratio of the space volume in the unit volume to the volume of the solid electrolyte particles: the porosity), the denser the solid electrolyte is packed and the higher the ionic conductivity. The electrolyte of the present invention is a form in which a solid electrolyte is closely packed.

  The lithium ion conductive solid material used in the present invention is not particularly limited, and an organic compound, an inorganic compound, or a material composed of both organic and inorganic compounds can be used, and those known in the lithium ion battery field can be used. . Since lithium ion conductivity is high, lithium ion conduction generated from lithium sulfide and diphosphorus pentasulfide, or lithium sulfide and simple phosphorus and simple sulfur, as well as lithium sulfide, diphosphorus pentasulfide, simple phosphorus and / or simple sulfur It is preferable to use a conductive inorganic solid electrolyte. Hereinafter, a preferable solid electrolyte will be described.

  The lithium ion conductive inorganic solid electrolyte can be produced from lithium sulfide and diphosphorus pentasulfide and / or simple phosphorus and simple sulfur. Specifically, these raw materials are melt-reacted and then rapidly cooled, or a sulfide glass obtained by processing the raw materials by a mechanical milling method (hereinafter sometimes referred to as MM method) is heat-treated. It is.

As Li ₂ S, those commercially available without particular limitation can be used, but those having high purity are preferable as described below.
Lithium sulfide has at least a total content of lithium salt of sulfur oxide of 0.15% by mass or less, preferably 0.1% by mass or less, and a content of lithium N-methylaminobutyrate of 0.15% by mass. Hereinafter, it is preferably 0.1% by mass or less. When the total content of the lithium salt of sulfur oxide is 0.15% by mass or less, the obtained electrolyte is a glassy electrolyte (fully amorphous). That is, when the total content of the lithium salt of sulfur oxide exceeds 0.15% by mass, the obtained electrolyte is a crystallized product from the beginning, and the ionic conductivity of this crystallized product is low.
Furthermore, even if the crystallized product is subjected to the following heat treatment, the crystallized product is not changed, and a lithium ion conductive inorganic solid electrolyte having a high ion conductivity cannot be obtained.

Further, when the content of lithium N-methylaminobutyrate is 0.15% by mass or less, a deteriorated product of lithium N-methylaminobutyrate does not deteriorate the cycle performance of the lithium battery.
Therefore, in order to obtain a high ion conductive electrolyte, it is necessary to use lithium sulfide with reduced impurities.

The method for producing lithium sulfide used in the solid substance is not particularly limited as long as it is a method that can reduce at least the impurities.
For example, it can also be obtained by purifying lithium sulfide produced by the following method.
Among the following production methods, the method a or b is particularly preferable.
a. A method in which lithium hydroxide and hydrogen sulfide are reacted at 0 to 150 ° C. in an aprotic organic solvent to produce lithium hydrosulfide, and this reaction solution is then desulfurized at 150 to 200 ° C. -330312).
b. A method of directly producing lithium sulfide by reacting lithium hydroxide and hydrogen sulfide at 150 to 200 ° C. in an aprotic organic solvent (Japanese Patent Laid-Open No. 7-330312).
c. A method of reacting lithium hydroxide and a gaseous sulfur source at a temperature of 130 to 445 ° C. (Japanese Patent Laid-Open No. 9-283156).

There is no restriction | limiting in particular as a purification method of the lithium sulfide obtained as mentioned above. Preferable purification methods include, for example, International Publication No. WO2005 / 40039.
Specifically, the lithium sulfide obtained as described above is washed at a temperature of 100 ° C. or higher using an organic solvent.
The organic solvent used for washing is preferably an aprotic polar solvent, and more preferably, the aprotic organic solvent used for lithium sulfide production and the aprotic polar organic solvent used for washing are the same. .
Examples of the aprotic polar organic solvent preferably used for washing include aprotic polar organic compounds such as amide compounds, lactam compounds, urea compounds, organic sulfur compounds, cyclic organophosphorus compounds, Or it can use suitably as a mixed solvent. In particular, N-methyl-2-pyrrolidone (NMP) is selected as a good solvent.

The amount of the organic solvent used for washing is not particularly limited, and the number of times of washing is not particularly limited, but is preferably 2 or more. Cleaning is preferably performed under an inert gas such as nitrogen or argon.
The washed lithium sulfide is dried at a temperature equal to or higher than the boiling point of the organic solvent used for washing for 5 minutes or more, preferably about 2 to 3 hours or more under an inert gas stream such as nitrogen under normal pressure or reduced pressure. Thus, lithium sulfide used in the present invention can be obtained.

P ₂ S ₅ can be used without particular limitation as long as it is industrially manufactured and sold. In place of P ₂ S ₅ , elemental phosphorus (P) and elemental sulfur (S) in a corresponding molar ratio can also be used. Simple phosphorus (P) and simple sulfur (S) can be used without particular limitation as long as they are industrially produced and sold.

The mixing molar ratio of the lithium sulfide to diphosphorus pentasulfide or simple phosphorus and simple sulfur is usually 50:50 to 80:20, preferably 60:40 to 75:25.
Particularly preferably, it is about Li ₂ S: P ₂ S ₅ = 70: 30 (molar ratio).

As a method for producing sulfide glass, there are a melt quenching method and a mechanical milling method.
In the case of the melt quenching method, P ₂ S ₅ and Li ₂ S mixed in a predetermined amount in a mortar and pelletized are placed in a carbon-coated quartz tube and vacuum-sealed. After reacting at a predetermined reaction temperature, the glass is put into ice and quenched to obtain a sulfide glass.
The reaction temperature at this time is preferably 400 ° C to 1000 ° C, more preferably 800 ° C to 900 ° C.
Moreover, reaction time becomes like this. Preferably it is 0.1 to 12 hours, More preferably, it is 1 to 12 hours.
The quenching temperature of the reaction product is usually 10 ° C. or lower, preferably 0 ° C. or lower, and the cooling rate is about 1 to 10,000 K / sec, preferably 1 to 1000 K / sec.

In the case of the MM method, sulfide glass is obtained by mixing a predetermined amount of P ₂ S ₅ and Li ₂ S in a mortar and reacting for a predetermined time by a mechanical milling method.
The mechanical milling method using the above raw materials can be reacted at room temperature. According to the MM method, since a glassy electrolyte can be produced at room temperature, there is an advantage that a raw material is not thermally decomposed and a glassy electrolyte having a charged composition can be obtained.
Further, the MM method has an advantage that the glassy electrolyte can be made into fine powder simultaneously with the production of the glassy electrolyte.
Although various types of MM methods can be used, it is particularly preferable to use a planetary ball mill.
The planetary ball mill can efficiently generate very high impact energy by rotating the platform while the pot rotates.
Although the rotation speed and rotation time of the MM method are not particularly limited, the faster the rotation speed, the faster the glassy electrolyte production rate, and the longer the rotation time, the higher the conversion rate of the raw material into the glassy electrolyte.
The electrolyte thus obtained is a glassy electrolyte and usually has an ionic conductivity of about 1.0 × 10 ^{−5 to} 8.0 × 10 ⁻⁴ (S / cm).

As conditions for the MM method, for example, when a planetary ball mill is used, the rotational speed may be set to several tens to several hundreds of revolutions / minute, and the treatment may be performed for 0.5 hours to 100 hours.
Although specific examples of the sulfide glass by the melt quenching method and the MM method have been described above, manufacturing conditions such as temperature conditions and processing time can be appropriately adjusted according to the equipment used.

Thereafter, the obtained sulfide glass is heat-treated at a predetermined temperature to produce a solid electrolyte.
The heat treatment temperature for generating the solid electrolyte is preferably 190 ° C to 340 ° C, more preferably 195 ° C to 335 ° C, and particularly preferably 200 ° C to 330 ° C.
When the temperature is lower than 190 ° C., it may be difficult to obtain a crystal with high ion conductivity. When the temperature is higher than 340 ° C., a crystal with low ion conductivity may be generated.
The heat treatment time is preferably 3 to 240 hours, particularly preferably 4 to 230 hours, when the temperature is 190 ° C or higher and 220 ° C or lower. When the temperature is higher than 220 ° C and not higher than 340 ° C, 0.1 to 240 hours are preferable, 0.2 to 235 hours are particularly preferable, and 0.3 to 230 hours are more preferable.
If the heat treatment time is shorter than 0.1 hour, it may be difficult to obtain a crystal with high ion conductivity. If the heat treatment time is longer than 240 hours, a crystal with low ion conductivity may be formed.
The lithium ion conductive inorganic solid electrolyte thus obtained usually has an ionic conductivity of about 7.0 × 10 ^{−4 to} 5.0 × 10 ⁻³ (S / cm).

This lithium ion conductive inorganic solid electrolyte has 2θ = 17.8 ± 0.3 deg, 18.2 ± 0.3 deg, 19.8 ± 0.3 deg, X-ray diffraction (CuKα: λ = 1.5418４), It is preferable to have diffraction peaks at 21.8 ± 0.3 deg, 23.8 ± 0.3 deg, 25.9 ± 0.3 deg, 29.5 ± 0.3 deg, 30.0 ± 0.3 deg.
A solid electrolyte having such a crystal structure has extremely high lithium ion conductivity.

The lithium ion conductive solid material used in the present invention is a solid electrolyte containing a lithium (Li) element, a phosphorus (P) element and a sulfur (S) element, and the following (1) and (2) It is preferable to satisfy the following condition.
(1) The solid ³¹ PNMR spectrum of the solid electrolyte has peaks due to crystals at 90.9 ± 0.4 ppm and 86.5 ± 0.4 ppm.
(2) The ratio (x _c ) of crystals that produce the peak of (1) in the solid electrolyte is 60 mol% to 100 mol%.

The two peaks of condition (1) are observed when a high ion conductive crystal component is present in the solid electrolyte. Specifically, it is a peak caused by P ₂ S ₇ ^4- and PS ₄ ^3- in the crystal.

Condition (2) is used to define the ratio x _c of the crystal occupied in the solid electrolyte.
When a high ion conductive crystal component is present in a predetermined amount or more, specifically 60 mol% or more in the solid electrolyte, lithium ions move mainly through the high ion conductive crystal. Therefore, the lithium ion conductivity is improved as compared with the case of moving a non-crystalline portion (glass portion) in the solid electrolyte or a crystal lattice (for example, P ₂ S ₆ ⁴⁻ ) that does not exhibit high ion conductivity. The ratio _{x c} is preferably 65mol% ~100mol%.
The ratio x _c of the crystal can be controlled by adjusting the heat treatment time and temperature of the sulfide glass as a raw material.

The solid ³¹ PNMR spectrum is measured using, for example, a JNM-CMXP302 NMR apparatus manufactured by JEOL Ltd., the observation nucleus is ³¹ P, the observation frequency is 121.339 MHz, the measurement temperature is room temperature, and the measurement method is the MAS method. Do as.
Measurement method of ratio _{x c} is the solids ³¹ PNMR spectrum, the resonance lines observed in 70～120Ppm, separated into a Gaussian curve using non-linear least squares method is calculated from the area ratio of each curve. For details, refer to Japanese Patent Application No. 2005-356889.

In this solid electrolyte, the spin-lattice relaxation time T _1Li at room temperature (25 ° C.) measured by the solid ⁷ LiNMR method is preferably 400 ms or less. The relaxation time T _1Li is an index of molecular mobility in a solid electrolyte including a glass state or a crystalline state and a glass state, and when T _1Li is short, the molecular mobility increases. Accordingly, since lithium ions are easily diffused during discharge, ion conductivity is increased. In the present invention, as described above, since a high ion conductive crystal component is contained in a predetermined amount or more, T _1Li can be 400 ms or less. T _1Li is preferably 350 ms or less.

The spin-lattice relaxation time T _1Li of ⁷ Li can be obtained, for example, as follows.
When a JNM-CMXP302 NMR apparatus manufactured by JEOL Ltd. is used and measured under the following conditions, a ⁷ LiNMR spectrum having a peak in the range of 0-1 ppm is obtained.
NMR measurement conditions Observation nucleus: ⁷ Li
Observation frequency: 116.489 MHz
Measurement temperature: Room temperature (25 ° C)
Measurement method: Saturation recovery method (pulse sequence: see Fig. 1)
90 ° pulse width: 4μs
Magic angle rotation speed: 6000Hz
Wait time until the next pulse application after FID measurement: 5s
Accumulation count: 64 times The chemical shift is determined using LiBr (chemical shift-2.04 ppm) as an external reference.

Ｍ（τ）：τのときのピーク強度 T 1 _Li is determined by optimizing the change in the intensity of the peak obtained when measurement is performed while changing τ in FIG. 1 using the nonlinear least square method.

M (τ): Peak intensity at τ

This solid electrolyte is a nonflammable inorganic solid having a decomposition voltage of at least 10 V or more. In addition, while maintaining the characteristic that the lithium ion transport number is 1, it exhibits extremely high lithium ion conductivity of 10 ⁻³ S / cm level at room temperature. Therefore, it is extremely suitable as a material for a solid electrolyte of a lithium battery. Moreover, it is a solid electrolyte excellent in heat resistance.

The electrolyte of the present invention can be produced, for example, by forming a particulate lithium ion conductive solid material by a blast method or an aerosol deposition method. Also, a lithium ion conductive solid material can be formed by a cold spray method, a sputtering method, a vapor deposition method (CVD), a thermal spraying method, or the like. However, since the film can be formed in a temperature range that does not change the crystal state of the electrolyte under a simple apparatus or at room temperature, the above-described blasting method or aerosol deposition method is preferable.
Hereinafter, the manufacturing method by the blast method and the aerosol deposition method will be described.

1. Blasting method In the blasting method, a spray material (in the present invention, a lithium ion conductive solid substance) is sprayed onto an object to be processed (current collector in the present invention) by a blast processing apparatus, and the surface of the object to be processed is made of the spray material. A method of forming a layer.
As the blasting apparatus used in the present invention, a known apparatus used for sandblasting or the like can be used. For example, a direct pressure blasting apparatus can be used. About the injection nozzle used for a blast processing apparatus, it is preferable to use what satisfy | fills the requirements of following formula (1) and (2) from a viewpoint of the improvement of the injection speed of an injection material.

Here, the symbol in a formula shows the following. In addition, when there is a subscript in the symbol, those with 1 as a subscript indicate values at the injection nozzle inlet, those with 2 as a subscript indicate values at the injection nozzle outlet, and those without a subscript are The value at the arbitrary position x is shown.
g: Gravitational acceleration g = 9.8 [m / sec ² ]
κ: Specific heat ratio of gas [(c _p / c _v )]
R: Gas constant [kJ / (kg · K)]
T ₁ : temperature of gas at the injection nozzle inlet [K]
p: Gas pressure [Pa] at an arbitrary position x from the injection nozzle inlet
p ₁ : Gas pressure [Pa] at the injection nozzle inlet
p ₂ : Gas pressure [Pa] at the outlet of the injection nozzle
G: Gas weight flow rate [N / sec]
x: Arbitrary position from the injection nozzle inlet [m]
L: Injection nozzle length [m]

Incidentally, in the present _{embodiment, κ = 1.4, R = 286.85J} / kg · K, T 1 = 293K, p 1 = 1.08MPa, p 2 = 0.10MPa, L = 0.024m, d = φ3 = 0.003 m. As a _{result, p t = p c = 0.57kgf} / cm 2, T t = T c = 244K, w t = 313m / sec, a t = 7.1 × 10 -6 m 2, G = 1.73N / sec.
About a blast processing apparatus, Unexamined-Japanese-Patent No. 2005-144656 and a shape material (2005.:12:17-17) can be referred.

In the present invention, the jetting speed of the propellant during blasting is preferably 150 m / sec to 450 m / sec, preferably 200 m / sec to 300 m / sec. Within this range, the electrolyte can be preferably formed as a solid electrolyte thin film layer on a current collector such as aluminum or copper.
The injection pressure is preferably 0.01 MPa to 5 MPa. More preferably, it is 0.1 MPa to 2 MPa. If it is this range, the thin film formation of a solid electrolyte is possible and it is preferable.
The average particle diameter of the propellant is preferably 0.1 μm to 100 μm, more preferably 1 μm to 50 μm. The average particle diameter means a value obtained by dispersing a raw material powder in a toluene solvent and measuring with a laser diffraction particle size distribution measuring apparatus (model number: Mastersizer 2000, manufactured by Sysmex Corporation). If it is this range, the thin film layer of a favorable solid electrolyte can be formed.

2. Aerosol deposition method Aerosol deposition method is an electrolyte consisting of lithium ion conductive solid material by mixing fine particles or ultrafine particles of lithium ion conductive solid material with gas to form an aerosol, and spraying it through a nozzle to a current collector. A method of forming a layer. According to this method, the electrolyte layer can be formed without exposing the lithium ion conductive solid material to a high temperature.
The apparatus and film forming conditions used in the aerosol deposition method are described in, for example, Japanese Patent Application Laid-Open No. 2001-3180, AIST Today (public relations magazine of AIST), vol. 4 No. You can refer to 8 Topics.

B. Battery Member The battery member of the present invention is used as a solid electrolyte layer of an all-solid secondary battery, and has a current collector and an electrolyte layer on at least a part of the current collector. And an electrolyte layer consists only of lithium ion conductive solid substance, and the film thickness of an electrolyte layer is 500 micrometers or less.

  In the present invention, the current collector is a plate or foil made of copper, magnesium, stainless steel, titanium, iron, cobalt, nickel, zinc, aluminum, germanium, indium, lithium, or an alloy thereof. Can be used.

In the battery member of the present invention, at least a part of the current collector has an electrolyte layer substantially made only of a lithium ion conductive solid material. The electrolyte layer is the above-described electrolyte of the present invention.
By forming the electrolyte layer in this way, the ion conductivity of the battery member can be improved.

C. Electrode In the solid pole material, in order to improve the ionic conductivity in addition to the electron conductivity, the particles of the pole material are in close contact with each other, and there are many junctions and surfaces between the particles to secure more ion conduction paths. It is important to. Therefore, a method of mixing an ion conductive active material such as an electrolyte to make an electrode material is also used. Further, the smaller the space generated in the gaps between the polar material particles (the ratio of the volume of the polar material particles to the volume of the polar material particles: the porosity), the denser the polar material layer is and the higher the ionic conductivity.

In the present invention, the same current collector as that described above can be used as the current collector.
As a material for forming the electrode material layer, there are a positive electrode material and a negative electrode material.
As a positive electrode material, what is used as a positive electrode active material in the battery field | area can be used. For example, in the sulfide system, titanium sulfide (TiS ₂ ), molybdenum sulfide (MoS ₂ ), iron sulfide (FeS, FeS ₂ ), copper sulfide (CuS), nickel sulfide (Ni ₃ S ₂ ), and the like can be used. Preferably, TiS ₂ can be used.
In the oxide system, bismuth oxide (Bi ₂ O ₃ , Bi ₂ Pb ₂ O ₅ ), copper oxide (CuO), vanadium oxide (V ₆ O ₁₃ ), lithium cobaltate (LiCoO ₂ ), lithium nickelate ( LiNiO ₂ ), lithium manganate (LiMnO ₂ ) and the like can be used. It is also possible to use a mixture of these. Preferably, lithium cobaltate can be used.
In addition to the above, niobium selenide (NbSe ₃ ) can be used.

As a negative electrode material, what is used as a negative electrode active material in the battery field | area can be used. For example, carbon materials, specifically, artificial graphite, graphite carbon fiber, resin-fired carbon, pyrolytic vapor-grown carbon, coke, mesocarbon microbeads (MCMB), furfuryl alcohol resin-fired carbon, polyacene, pitch-based carbon Examples include fibers, vapor grown carbon fibers, natural graphite, and non-graphitizable carbon. Or it may be a mixture thereof. Preferably, it is artificial graphite.
Moreover, you may mix and use the solid electrolyte used for an electrolyte layer with an pole material.

The electrode of the present invention can be produced by forming the positive electrode material or the negative electrode material in a film shape on at least a part of the current collector. Examples of the film forming method include a blast method, an aerosol deposition method, a cold spray method, a sputtering method, a vapor deposition method, and a thermal spray method, as in the production of the battery member described above. By forming a film by such a method, the porosity of the electrode material layer can be further reduced, and the ionic conductivity can be improved.
The blasting method and the aerosol deposition method are preferred because the film can be formed in a temperature range that does not change the crystal state of the electrolyte under a simple apparatus and room temperature conditions.

D. All-solid secondary battery The all-solid-state secondary battery of the present invention has at least one of the above-described electrolyte, the battery member, and the electrode of the present invention.
In addition, a pair of electrodes composed of a positive electrode and a negative electrode, and an electrolyte layer between the positive electrode and the negative electrode, the electrolyte layer is substantially made only of a lithium ion conductive solid material, and the thickness of the electrolyte layer is 500 μm or less. is there.
FIG. 2 is a configuration diagram of an embodiment of the all solid state secondary battery of the present invention.
The all-solid-state secondary battery 10 has a configuration in which an electrolyte 40 is sandwiched between a pair of electrodes composed of a positive electrode 20 and a negative electrode 30. The positive electrode 20 includes a current collector 21 and a positive electrode material 22, and the negative electrode 30 includes a current collector 31 and a negative electrode material 32. These are the electrodes of the present invention. The electrolyte 40 includes a current collector 41 and a solid electrolyte layer 42, and is sandwiched between the positive electrode material 22 and the negative electrode material 32.

In addition, in this embodiment, although the electrode and battery member of the present invention described above are used, the present invention is not limited to this, and only one of the electrode or battery member may be used. When the battery member of the present invention is used, a lithium ion all solid secondary battery is obtained.
Further, the current collectors 21, 31, and 41 may be the same or different. For example, a copper foil may be used for the current collector 31, and an aluminum foil may be used for the current collectors 21 and 41.
Further, the current collector 41 can be omitted.

The all-solid-state secondary battery of the present invention can be produced by bonding and joining the above-described battery member and / or electrode members of the present invention. As a method of joining, there are a method of laminating each member, pressurizing and pressure bonding, a method of pressing through two rolls (roll to roll), and the like.
Moreover, you may join to the joining surface through the active material which has ion conductivity, and the adhesive material which does not inhibit ion conductivity.
In joining, heat fusion may be performed as long as the crystal structure of the solid electrolyte does not change.

The all solid state secondary battery of the present invention becomes a practical level all solid state battery by joining the above battery members and / or electrodes.
Further, since the battery of the present invention can be thinned, it can be stacked to obtain a high output. Furthermore, a high degree of integration is possible.

Hereinafter, the present invention will be described more specifically with reference to examples.
In addition, about evaluation of ion conductivity and a battery characteristic, it carried out by the method described in the Example of international publication 2005/119706.
Formation of the solid electrolyte layer using blasting, formation of the electrode material, measurement of the formed film thickness, and the like were performed by the methods described in Examples of JP-A-2005-144556.

Production Example 1 (Production of lithium ion conductive solid material)
(1) Production of lithium sulfide Lithium sulfide was produced according to the method of the first aspect (two-step method) of JP-A-7-330312.
Specifically, N-methyl-2-pyrrolidone (NMP) 3326.4 g (33.6 mol) and lithium hydroxide 287.4 g (12 mol) were charged into a 10-liter autoclave equipped with a stirring blade at 300 rpm. The temperature was raised to 130 ° C.
After the temperature rise, hydrogen sulfide was blown into the liquid at a supply rate of 3 liters / minute for 2 hours.
Subsequently, this reaction solution was heated in a nitrogen stream (200 cm ³ / min), and a part of the reacted hydrogen sulfide was dehydrosulfurized.
As the temperature increased, water produced as a by-product due to the reaction between hydrogen sulfide and lithium hydroxide started to evaporate, but this water was condensed by the condenser and extracted out of the system.
While water was distilled out of the system, the temperature of the reaction solution increased, but when the temperature reached 180 ° C., the temperature increase was stopped and the temperature was kept constant.
After the dehydrosulfurization reaction was completed (about 80 minutes), the reaction was completed to obtain lithium sulfide.

(2) Purification of lithium sulfide After decanting NMP in the 500 mL slurry reaction solution (NMP lithium monosulfide slurry) obtained in (1) above, 100 mL of dehydrated NMP was added and stirred at 105 ° C. for about 1 hour. .
NMP was decanted at this temperature.
Further, 100 mL of NMP was added and stirred at 105 ° C. for about 1 hour. NMP was decanted at this temperature, and the same operation was repeated 4 times in total.
After completion of decantation, the film was dried at 230 ° C. under reduced pressure for 3 hours.

The impurity content in the obtained lithium sulfide was quantified by ion chromatography. As a result, lithium sulfite (Li ₂ SO ₃ ) is less than 0.0008 mass%, lithium sulfate (Li ₂ SO ₄ ) is less than 0.001 mass%, and lithium thiosulfate (Li ₂ S ₂ O ₃ ) is 0.001. Less than wt%, lithium N-methylaminobutyrate (LMAB) was 0.04 wt%.

(3) Production of Lithium Ion Conductive Solid Material Li ₂ S and P ₂ S ₅ (manufactured by Aldrich) purified in the above production example were used as starting materials. About 50 g of a mixture obtained by adding 70 mol parts of Li ₂ S and 30 mol parts of P ₂ S ₅ and 175 alumina balls having a particle diameter of 10 mmΦ are placed in a 500 mL alumina container, and a planetary ball mill (manufactured by Fritsch: In model No. P-5), by rotating the rotational speed at 290 rpm at room temperature (25 ° C.) in a nitrogen atmosphere and performing mechanical milling for 36 hours (energy is 38.5 kWh / kg electrolyte), A sulfide-based glass was obtained as a powder.
Powder X-ray diffraction measurement was performed on the obtained powder (CuKα: λ = 1.5418Å). As a result, it was confirmed that the crystal peak of Li ₂ S completely disappeared and was vitrified. This X-ray diffraction spectrum is shown in FIG.

This glass powder was put in a sealed container and heat-treated at 300 ° C. for 2 hours to obtain a lithium ion conductive solid material. As described above, powder X-ray diffraction measurement was performed, and as a result, a crystal peak shown in FIG. 4 was obtained.
The ionic conductivity of the obtained electrolyte was 2 × 10 ⁻³ S / cm.

Example 1 (solid electrolyte layer)
A thin film layer of a solid electrolyte was formed on an aluminum plate by blasting using the same method as in Example 4 of JP-A-2005-144666. Specifically, a thin film of the lithium ion conductive solid material produced in Production Example 1 was formed on an aluminum plate having a thickness of 5 mm × 5 mm × 1 mm as a current collector to form an electrolyte layer. The average particle size of the solid material used was 15 μm. The conditions of the blast method were an injection pressure of 1.5 MPa, an injection speed of 300 m / sec, and an injection distance of 50 mm.

When the film thickness of the electrolyte layer was observed with a transmission electron microscope apparatus (FE-TEM), the average film thickness was 2 μm. In addition, the average film thickness was observed at 10 points at random by FE-TEM, and the average value was taken.
The ion conductivity of the solid electrolyte layer was measured and found to be 6 × 10 ⁻⁴ S / cm.

Example 2 (positive electrode)
A positive electrode was produced by the blast method in the same manner as in Example 1. Specifically, a mixture of lithium cobalt oxide and the lithium ion conductive solid material of Production Example 1 at a weight ratio of 8: 5 is used as the positive electrode material, and an aluminum plate having a thickness of 5 mm × 5 mm × 1 mm is used as the current collector. did. The blasting conditions were the same as in Example 1 except that the injection speed was changed to 270 m / sec.
When the film thickness of the electrolyte layer was observed with a transmission electron microscope (FE-TEM), the positive electrode material layer of the obtained positive electrode had an average film thickness of 200 μm and a thin film was formed.

Example 3
The measurement cell was assembled as follows, and the operability as a secondary battery was confirmed. Specifically, the solid electrolyte member produced in Example 1 was cut out into a disk having a diameter of 1 cm. The electrode prepared in Example 2 was cut out into a disk having a diameter of 1 cm. The surface of the electrolyte layer of the solid electrolyte member and the surface of the electrode material layer of the electrode were combined and joined (the electrode of Example 2 was used as the positive electrode).
Next, a lithium metal foil having a diameter of 1 cm and a thickness of 0.5 mm is bonded on the aluminum collector of the solid electrolyte layer, and a copper foil having a diameter of 1 cm and a thickness of 0.5 mm is further formed on the lithium metal foil. Bonding was made into a negative electrode.
The battery characteristics of the measurement cell thus produced were evaluated.
As a result of charging and discharging the measurement cell with a constant current of 50 μA, it was confirmed that the measurement cell was operated as a secondary battery.

The electrolyte, battery member and electrode of the present invention can be used for all solid state secondary batteries.
The all-solid-state secondary battery of the present invention can be used as a battery for a portable information terminal, a portable electronic device, a small electric power storage device for home use, a motorcycle using a motor as a power source, an electric vehicle, a hybrid electric vehicle, or the like.

It is a figure which shows the pulse series at the time of relaxation time measurement. It is a block diagram of the all-solid-state secondary battery of one Embodiment of this invention. 2 is an X-ray diffraction spectrum of sulfide glass. 2 is an X-ray diffraction spectrum of a lithium ion conductive solid material.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 All-solid-state secondary battery 20 Positive electrode 21 Current collector 22 Positive electrode material 30 Negative electrode 31 Current collector 32 Negative electrode material 40 Electrolyte 41 Current collector 42 Solid electrolyte

Claims (6)

  An electrolyte consisting essentially of a lithium ion conductive solid material and having a film thickness of 500 μm or less.   The electrolyte according to claim 1 formed by a blast method or an aerosol deposition method.   A battery member comprising the current collector and the electrolyte according to claim 1 at least at a part of the current collector.   An electrode having a current collector and an electrode material layer formed on at least a part of the current collector by a blast method or an aerosol deposition method.   The all-solid-state secondary battery which has at least 1 of the electrolyte in any one of Claims 1-4, the member for batteries, and an electrode.   The all-solid-state secondary battery according to claim 5, wherein the electrolyte is made of lithium sulfide and diphosphorus pentasulfide and / or simple phosphorus and simple sulfur.

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